Abstract
Three species of the C4 grass genus Muhlenbergia from the forest understory—M. frondosa, M. sobolifera,
and M. schreberi—and one species from an open prairie, M. cuspidata, were transplanted to a sunny
common garden and to a forest understory. After 4 mo of growth, all species in the common garden produced
more biomass and greater leaf area and number than those in the understory. Muhlenbergia cuspidata died
in the understory. Chlorophyll (chl) concentrations were higher, and a/b ratios were lower, in plants from
the understory. All species were grown in the laboratory under two PPFD regimes: (1) 15 |xmol m~2 s _ l
for 9 h plus two 10-min periods of 500 |xmol m~2 s _ 1 ; and (2) 15 fimol m~2 s _ l for 20 h. Total integrated
PPFD, not peak photon flux density, appeared to determine all aspects of the photosynthetic responses of
these plants. Characteristics of photosynthetic gas exchange in situ for M. frondosa and M. sobolifera were
similar to laboratory findings. Although results indicated that the three understory species adjusted their chl
characteristics and survived when grown under low levels of PPFD, they grew optimally under the higher
PPFD.
Description
This is the official publisher's version, also available electronically from: http://www.jstor.org/stable/10.2307/2995300.